Regex Tester
Test JavaScript regular expressions with live highlighting, capture groups, replace preview and Indian presets.
About Regex Tester
This regex tester lets you write and test JavaScript regular expressions against your own text. Matches are highlighted as you type, each capture group is listed, and a replace preview shows the result of a substitution. Set flags such as global, case-insensitive and multiline as needed.
Ready-made presets cover common patterns, including email, Indian mobile number, PAN, GSTIN and PIN code, which you can use as a starting point. It is useful for developers building form validation, data cleaning scripts and search patterns. The tester is free, needs no sign-up and runs in your browser.
How to use Regex Tester
- Type a pattern or pick a preset (email, PAN, GSTIN…).
- Set the flags you need.
- Edit the test text — matches highlight instantly.
- Check groups in the match list and try a replacement.
Frequently asked questions
Which regex flavour is this?
JavaScript (ECMAScript), as used in browsers and Node.js. Most syntax matches PCRE and Python, but lookbehind and named groups follow JavaScript rules.
What do the flags mean?
g finds all matches, i ignores case, m makes ^ and $ match at line breaks, s lets . match newlines, u enables full Unicode, y is sticky.
How do I use groups in the replacement?
Use $1, $2 for numbered groups,
How do I test a regular expression online?
Type your pattern, set the flags and paste sample text; every match is highlighted instantly with its groups listed below.
What is the regex for an Indian mobile number?
A common pattern is ^[6-9]\d{9}$, which matches 10 digits starting with 6, 7, 8 or 9. Pick the preset to try it.
Will a JavaScript regex work in Python or Java?
Most basic syntax is the same, but features such as lookbehind and named groups can differ slightly, so test in the target language too.
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